In recent years, various types of treatments and diagnoses in the medical field have been performed using an elongated and hollow tubular-shaped medical instrument called a catheter. Examples of such treatment methods include directly administering an agent into an affected area using the elongated configuration of the catheter, push-opening a narrowed section in the lumen in a living body using a catheter in which a balloon dilated by pressure is attached to a distal end of the catheter, scraping and opening the affected area using a catheter in which a cutter is attached to a distal portion of the catheter, and closing arterial aneurysm, bleeding, or feeding blood vessel sites with a filling material using the catheter. Other examples also include a treatment method of embedding and placing a tubular-shaped stent which has a mesh-shaped side surface into the lumen in the living body using the catheter so as to maintain an open state of the narrow section in the lumen in the living body. Further, examples include aspirating a thrombus within the blood vessels.
In general, an introducer is used in a case where the treatment, diagnosis, or the like is performed using the catheter. The introducer has an introducer sheath including a sheath tube introduced to a puncture site; a dilator which is inserted into a lumen of the sheath tube; and a three-way stopcock portion which is provided so as to be communicated with the lumen of the sheath tube. An example is disclosed in Japanese Application Publication No. 6-48684. The sheath tube is introduced to a puncture site which is formed on an arm or a leg and a catheter or the like is percutaneously inserted into a lesion site such as the blood vessel through the lumen of the sheath tube.
In general, the introducer is color-coded based on a color code. The color code shows a maximum diameter of a device (medical instrument such as a catheter) that can be inserted into the lumen of the sheath tube in the introducer sheath using colors.